# operator+,-(ranges::enumerate_view::iterator)

From cppreference.com
< cpp‎ | ranges‎ | enumerate view‎ | iterator

friend constexpr /* iterator */ operator+( const /* iterator */& i, difference_type n ) requires ranges::random_access_range</* Base */>; | (1) | (since C++23)
friend constexpr /* iterator */ operator+( difference_type n, const /* iterator */& i ) requires ranges::random_access_range</* Base */>; | (2) | (since C++23)
friend constexpr /* iterator */ operator-( const /* iterator */& i, difference_type n ) requires ranges::random_access_range</* Base */>; | (3) | (since C++23)
friend constexpr difference_type operator-( const /* iterator */& i, const /* iterator */& j ) noexcept; | (4) | (since C++23)

Performs iterator arithmetic or calculates the distance.

`pos_` is the underlying index, and `Base` is the (possibly const-qualified) type of underlying view.

Equivalent to:

1) auto temp = i; temp += n; return temp;
2) return i + n;
3) auto temp = i; temp -= n; return temp;
4) return i.pos_ - j.pos_;

These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when `enumerate_view::iterator<Const>` is an associated class of the arguments.

### Parameters

i, j | - | the iterators
n | - | position relative to current location

### Return value

1,2) An incremented iterator.
3) A decremented iterator.
4) A distance between given iterators.

### Example

| This section is incomplete Reason: no example

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 3912 | C++23 | overload (4) was not noexcept | it is noexcept

### See also

operator++operator++(int)operator--operator--(int)operator+=operator-= | advances or decrements the underlying iterator (public member function)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/ranges/enumerate_view/iterator/operator_arith2&oldid=172623"